Building block



FIG. 1 is a perspective view of a building block showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a front elevational view thereof;

FIG. 6 is a right side elevational view with the left side view beingthe same thereas; and,

FIG. 7 is a cross-sectional view taken on line 7—7 of FIG. 2.

The ornamental design for a building block, as shown and described. 